FIG. 2.

Polymorphic sites in the nine clones prepared from the 80th-passage virus. The nucleotide positions are ordered along the vertical axis corresponding to changes observed in the PCR consensus sequence (upper 15) and those that were not observed in the consensus sequence (lower 7). Each of columns 1 to 9 represents a different clone corresponding to a different viral isolate. A black square denotes the evolved (nonancestral) base, which changed as indicated in Fig. 1. All of the clones have unique sequences, which is suggestive of recombination.